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<head><meta charset="utf-8"><title>Help getting #84767 (my `?` PR) ready for merge · t-compiler/help · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/index.html">t-compiler/help</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Help.20getting.20.2384767.20(my.20.60.3F.60.20PR).20ready.20for.20merge.html">Help getting #84767 (my `?` PR) ready for merge</a></h3>

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<a name="237220504"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Help%20getting%20%2384767%20%28my%20%60%3F%60%20PR%29%20ready%20for%20merge/near/237220504" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> scottmcm <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Help.20getting.20.2384767.20(my.20.60.3F.60.20PR).20ready.20for.20merge.html#237220504">(May 03 2021 at 20:05)</a>:</h4>
<p>Hi folks!  I've gotten my PR for the new <code>?</code> desugaring done enough to get through CI &amp; a try build, but now I'm at the point where I think I need advice to finalize it.</p>
<ul>
<li>
<p>I did a <a href="https://perf.rust-lang.org/compare.html?start=59f551a2dcf57c0d3d96ac5ef60e000524210469&amp;end=9e1fbcd2d92fbe606de781106bb28b5c1e981c0a">perf run</a>, and while it's sometimes 2% better, it looks like it's overall a bit worse, so I'd appreciate suggestions on how I should figure out what's up there.</p>
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<li>
<p>I added a bunch of <code>rustc_on_unimplemented</code> that mean most of the error messages are <a href="https://github.com/rust-lang/rust/pull/84767/files#diff-51c8fb66fa779e1d29208d988bf59e70994eb631a1cd9a65ee66c9e60db440c7R1-R13">pretty good</a> IMHO, but there are a few that lost some of the special <code>?</code> updates.  How much of that needs to be fixed as part of this PR?  (Some of them I'm uncertain about, since things like "note: <code>?</code> implicitly converts the error value" aren't technically correct, so maybe need to be made Result-specific?)  And for things like the ones in inference, I could use some assistance in understanding how to fix them.</p>
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<li>
<p>Who's the right person to review it all?  There are enough places that care about <code>?</code> (codegen tests, mir tests, clippy lints, ...) that this ended up touching a whole bunch of stuff, and I couldn't figure out a great way to split it further.</p>
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<a name="237220740"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Help%20getting%20%2384767%20%28my%20%60%3F%60%20PR%29%20ready%20for%20merge/near/237220740" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Joshua Nelson <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Help.20getting.20.2384767.20(my.20.60.3F.60.20PR).20ready.20for.20merge.html#237220740">(May 03 2021 at 20:07)</a>:</h4>
<p><span class="user-mention silent" data-user-id="125270">scottmcm</span> <a href="#narrow/stream/182449-t-compiler.2Fhelp/topic/Help.20getting.20.2384767.20.28my.20.60.3F.60.20PR.29.20ready.20for.20merge/near/237220504">said</a>:</p>
<blockquote>
<ul>
<li>I did a <a href="https://perf.rust-lang.org/compare.html?start=59f551a2dcf57c0d3d96ac5ef60e000524210469&amp;end=9e1fbcd2d92fbe606de781106bb28b5c1e981c0a">perf run</a>, and while it's sometimes 2% better, it looks like it's overall a bit worse, so I'd appreciate suggestions on how I should figure out what's up there.</li>
</ul>
</blockquote>
<p>the details screen shows a heavy regression on <code>type_op_prove_predicate</code> - maybe take a look into that? <a href="/user_uploads/4715/Lq8em2DAiWq7Fg0s9_R1l3-r/image.png">image.png</a></p>
<div class="message_inline_image"><a href="/user_uploads/4715/Lq8em2DAiWq7Fg0s9_R1l3-r/image.png" title="image.png"><img src="/user_uploads/4715/Lq8em2DAiWq7Fg0s9_R1l3-r/image.png"></a></div>



<a name="237220753"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Help%20getting%20%2384767%20%28my%20%60%3F%60%20PR%29%20ready%20for%20merge/near/237220753" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Joshua Nelson <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Help.20getting.20.2384767.20(my.20.60.3F.60.20PR).20ready.20for.20merge.html#237220753">(May 03 2021 at 20:07)</a>:</h4>
<p>^ this screenshot is from diesel</p>



<a name="237220784"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Help%20getting%20%2384767%20%28my%20%60%3F%60%20PR%29%20ready%20for%20merge/near/237220784" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Joshua Nelson <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Help.20getting.20.2384767.20(my.20.60.3F.60.20PR).20ready.20for.20merge.html#237220784">(May 03 2021 at 20:08)</a>:</h4>
<p><code>type_op_normalize_predicate</code> too</p>



<a name="237220907"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Help%20getting%20%2384767%20%28my%20%60%3F%60%20PR%29%20ready%20for%20merge/near/237220907" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Joshua Nelson <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Help.20getting.20.2384767.20(my.20.60.3F.60.20PR).20ready.20for.20merge.html#237220907">(May 03 2021 at 20:08)</a>:</h4>
<p>the cargo one just looks like noise from CGUs, I wouldn't worry about it too much</p>



<a name="237221176"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Help%20getting%20%2384767%20%28my%20%60%3F%60%20PR%29%20ready%20for%20merge/near/237221176" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Joshua Nelson <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Help.20getting.20.2384767.20(my.20.60.3F.60.20PR).20ready.20for.20merge.html#237221176">(May 03 2021 at 20:10)</a>:</h4>
<blockquote>
<p>I added a bunch of rustc_on_unimplemented that mean most of the error messages are pretty good IMHO, but there are a few that lost some of the special ? updates. How much of that needs to be fixed as part of this PR? (Some of them I'm uncertain about, since things like "note: ? implicitly converts the error value" aren't technically correct, so maybe need to be made Result-specific?) And for things like the ones in inference, I could use some assistance in understanding how to fix them.</p>
</blockquote>
<p>I would tag <span class="user-mention silent" data-user-id="119031">Esteban Küber</span> on the PR maybe</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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